1. Field of the Invention
This invention relates to fluid propulsion and, more particularly, to a bladed, rotary apparatus through which an intercepted fluid is centrifugally propelled with respect to a rotary axis.
2. Background Art
Bladed, centrifugal-type rotary apparatus are used in many different environments to propel fluids that may be in liquid or gaseous form. As an example, this type of rotary apparatus is used on furnaces to both direct heated air into a space to be conditioned and exhaust combustion products to an external environment.
There are currently several different ways that such bladed, rotary apparatus are constructed. For example, it is known to mold such a rotary apparatus in one piece from metal or plastic. Particularly in the case of metal, this can be a relatively expensive process.
It is also known to form this type of rotary apparatus from a single metal sheet. The sheet can be struck through at the outlines of the blades which are then bent generally at right angles to the plane of the sheet. While the apparatus can be formed economically using this method, it has one particular drawback. The axial extent of the blades is inherently limited by the geometry of the sheet. As the number of blades increases, the permissible axial extent thereof is correspondingly decreased.
It is also known to form a rotary apparatus by providing a flat support and attaching individual blades that are separately formed from the base. An example of this type of construction is shown in U.S. Pat. No. 3,127,094.
A drawback with this latter design is that by reason of having to individually attach each blade, there is a possibility that optimal alignment may not be achieved between each blade and the other blades and rotary axis. Resultingly, this structure is prone to being dynamically imbalanced. Also, the manufacturing process for such an apparatus is inherently complicated by reason of having to install the multiple blade components with multiple separate fasteners. This translates into additional costs that may have to be passed on to the consumer.
The industry continues to seek out designs of rotary, bladed, centrifugal-type apparatus that can be made economically and with consistent operating characteristics to meet different design criteria.